Opinion: 2015 Mustang Weight

Heavy Remorse

If the 2015 Mustang is heavier than its predecessor, would it really be a surprise?

By Steve Turner

Photos courtesy of Ford Motor Company

If the Internet had a favorite car, you’d have to think the Mustang is one of the leading candidates for that title. This is especially true during the news-cycle courtship that takes place leading up to the release of an all-new Mustang. With a public hungry for new intelligence, the vacuum left between official news releases creates a viral breeding ground.

Last week rumors that the 2015 Mustang would be heavier than its predecessor exploded to temporarily fill that void. Now, it doesn’t take much to get people excited about a new Mustang, which is great. However, I have to say that I was taken aback by the seeming shock over the slightest possibility that the car would be heavier.

Would anyone really be surprised if the independently suspended 2015 Mustang was a little heavier than the outgoing 2014 Mustang?

Really? This would be a surprise?

I was always perplexed by the rumors that the car would be lighter. I’m not really sure how that started. Maybe someone heard something about a pre-production car? Who knows? However, I never really believed that the Mustang could gain an independent rear suspension and somehow end up lighter. Sure, it is possible if Ford turned to lighter, more expensive materials. However, there are costs to consider as well—though Ford’s lightweight Fusion concept portends a corporate diet…

The last Mustang to feature an independent rear suspension was the Terminator. Guess what, it weighed more than a comparable Mustang GT with a solid axle.

All this started because of a post assuming an IRS Mustang would be heavier. This is not a wild stretch of the imagination. In fact, we need only look back to the last IRS Mustang—the 2003-2004 Mustang Cobra. Way back then, the 2004 Mustang GT weighed in at only 3,317 pounds. It was a flyweight compared to the outgoing 2014 Mustang GT, which tips the scales at 3,618 pounds.

No one is complaining that the heavier 2014 gives up any performance to the 2004. Granted the powertrains are vastly different, but the fact remains the heavier car is a superior performer. However, both the 2004 and the 2014 are eclipsed by the weight of the 2003-2004 Cobra. It crossed the scales at 3,665 pounds. Sure, some of that mass was courtesy of the iron block, supercharger, and support hardware. However, at least 80 pounds of it was from the independent rear suspension. For example, the naturally aspirated 2001 Cobra was still 193 pounds heavier, at 3,430 pounds, than its 3,237-pound GT sibling with the solid axle.

That’s exactly why I was never there with the rest of the media complaining that the Mustang rear suspension was “antiquated” every time a new car was released. Even as the Boss 302 took solid-axle handling to new heights, the question still came up at every media launch. Now, I’m not saying that an IRS doesn’t work. A properly executed independent rear suspension works well, especially on uneven surfaces. Those bumpy roads are the Achilles’ heel of the solid axle.

You asked for it, you got it: all 2015 Mustangs will have independent rear suspensions.

Of course, I say properly executed, because even Ford engineers admit the Cobra’s IRS was a compromised design. In my experience, its combination of spring and damper tuning was so taut that it mitigated the benefits of the IRS on rough surfaces. The same could be said of my limited experiences in the early versions of the modern Camaros, though they have obviously come a long way.

Back in 2003-2004, the Cobra IRS weighed about 80 pounds more than a solid axle.

So an IRS can obviously improve the handling of the Mustang, but at what cost? Well, weight, expense, and drag strip limitations are the potential down sides. It certainly remains to be seen how these potential opportunity costs will play out on the S550. However, it will be interesting to see the mainstream auto media transition its long-running rear suspension complaint to one of excess weight, because the weight can likely be attributed directly to the suspension they demanded for so many years.

Yes, you can have an independent rear suspension, but don’t expect it to come without sacrificing something.

Now, lest you think I am joining the chorus of those complaining about weight, I’m not. Yes, I would love it if the new Mustang were lighter. I just never bought into that. In the end, if the Performance Pack-equipped Mustang GT handily outruns the vaunted Boss 302, the noise about weight will quiet. Dropping weight will improve performance, but if the performance is impressive the weight is less of an issue. You need look no further than the comparatively portly GT500 to see that.

The solid axle and the Mustang part ways at the close of the 2014 model year. Many have complained that the Mustang needed an independent rear suspension. Will the benefits of the IRS mitigate the additional weight and complexity?

So what is more important to you—a lighter Mustang or an independent rear suspension? Don’t say both, ’cause that’s just cheating reality.

Though it is not a Mustang, let’s hope the Ford Lightweight Vehicle concept foreshadows a diet for the pony car in the future.

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19 thoughts on “Opinion: 2015 Mustang Weight”

I have always been well aware of the complaints across the media about the lack of IRS in the Mustang following launches. But I never connected the weight issue and the IRS making the car heavier but it does make sense. I was shocked to hear the rumor of a heavier car again seeing that everything I had heard to this point said lighter. I would like to see a lighter Mustang. I don’t see the use of the IRS other than the ease of swapping exhausts (and I am an 2004 Cobra Owner). I feel like Ford has done a very nice job with the stick axles over the years and has been able to make them better along the way.

Well somewhere due to the F150 losing some 700 pounds the rumor mill started that the 2015 Stang was going to be 3-400 pounds lighter. Seemed a little unrealistic, but the thought of a higher hp Coyote setup in a 3200 curb weight car was VERY appealing. The drag crowd does not want the IRS. Sure the small percentage of autocrosser/road racers etc. like the idea of a mustang with IRS. But, it’s been proven time and again you can make a live axle handle with additional parts from the aftermarket. Ford is just trying to appeal to new international markets who expect independent suspension systems in newer cars. But, after finding out the reality of the weight gain (in addition to preferring the older retro styling myself) did change my mind on the newer 15 design. I just bought a new 2014 GT/CS myself. LOL

The problem with the live axle for Ford is the ride quality vs handling. They had basically reached the pinnacle of handling one could reasonably expect in a streetable car that appeals to the masses with the later S197s. They had simply run out of places to improve (considering that we’re dealing with a $25k base priced mass production car),

I never totally bought into the “less weight” rumor either, I just didn’t see how the car couldn’t gain some weight. But I still foresee the weight gain being around 100#, which is perfectly fine by me.

The IRS will weigh more, but it won’t weigh as much as the 99-04 IRS; this is a much better design that doesn’t require it’s own custom subframe. Obviously, Federal Safety standards will add weight as well. But Ford is also combating those weight gains with more use of aluminum in the front fenders, and the new double ball joint suspension will drop some weight over the old A-arm setup.

I’m willing to bet that the new front suspension drops as much weight as the new IRS adds.

yep let’s hope! Another area that you can see Ford trimming weight is through much less glass in the greenhouse. Specifically look at the rear window. The S197 rear glass is MUCH larger than the S550 rear glass.

Regarding the 2015 Mustang IRS (and Camaro and Challenger for that matter):
For the performance enthusiast that enjoys high powered rear drive cars, there is much more than weight to consider in the comparison of choice between IRS and stick axle design. Geometry is paramount, as is rigidity. In the spectrum of handling performance, the further toward the high end of the load scale one operates his car, where the reality becomes spirited driving on large tires, the higher G loads delivered through a compliant IRS geometry can cause handling surprises that require a chassis engineer/tuner to utilize much less compliant spring and damper settings, thus negating the ride comfort IRS supposedly delivers over a stick axle. This is due to the IRS inherent variations of load and thrust vectors at the tire’s foot print due to camber and toe changes during bump and roll, and deflections due to linkage compliance required to silence the suspension. These variables are why IRS race cars are generally unforgiving when they reach the limit, and are more sensitive to degrading tires. And for drag racers, even the local bracket racers, IRS is well known to not be effective or consistent in launch compared to a proper stick axle, and not as reliable (expensive to repair).
Today, most IRS handling quirks and deficiencies can be masked with electronic damping and stability control. But delivery of the total potential of the tire’s performance is still limited compared to a stick axle in most circumstances experienced by an enthusiast if the proper geometry and damping is employed in the design. This is particularly true for the enthusiast that drives on track. But alas, the motoring press which dictates the public demand through buzzword criticisms always has their way in the end. I find this to be unfortunate for those that desire a real “driver’s car.”
As the Mustang continues to gain sophistication, it becomes homogenized with BMW, and the “Bring Money With you” set is only so large. It is my opinion that this direction is away from the American performance driving enthusiast’s interest. There is a reason we rarely see many BMWs at our local drag strips that are currently flooded with Mustangs.

I still don’t see why Ford couldn’t get more weight out of the car like they did with the F-150. Aren’t they aware that enthusiasts were expending a lighter car? What a disappointment. I had planned on buying a’15, but now that’s off. I’ll find a ’14 to my linking.

I agree that Ford needs another ‘sports car’ like GT-40ish model. The ‘vette is kicking butt in road racing. It’s a shame Ford doesn’t have anything new to compete with it.

they produce so many F-150’s that the economies of scale allow them to use a high amount of aluminum in the body/chassis. Mustang sales are a fraction of F-150 sales; if they used that much aluminum in the Mustang the price would absolutely skyrocket.

they produce so many F-150's that the economies of scale allow them to use a high amount of aluminum in the body/chassis. Mustang sales are a fraction of F-150 sales; if they used that much aluminum in the Mustang the price would absolutely skyrocket.

they produce so many F-150's that the economies of scale allow them to use a high amount of aluminum in the body/chassis. Mustang sales are a fraction of F-150 sales; if they used that much aluminum in the Mustang the price would absolutely skyrocket.

Yes, but it’s what some of their engineers promised that leaves a bitter taste in the mouth. I have a feeling they knew it was going to be heavier and just lied about the reduced weight. I would be willing to pay more for a high-powered, lower weight mustang. But, it isn’t going to happen. They lost a customer. They’ve given GM the high ground and that hacks me off.

Yes, but it's what some of their engineers promised that leaves a bitter taste in the mouth. I have a feeling they knew it was going to be heavier and just lied about the reduced weight. I would be willing to pay more for a high-powered, lower weight mustang. But, it isn't going to happen. They lost a customer. They've given GM the high ground and that hacks me off.

When exactly did Ford engineers promise you it would be a smaller, lighter car? When is the last time any car got smaller and lighter over time? Seems to me that magazines made up those rumors to attract attention.

And how does GM get the high ground here? You must not be a true mustang fan if you’re all of a sudden like “well I loved Ford, but I think they lied to me so time to buy a Camaro”…